Polyester-spandex knitted fabrics have the advantages of good drape, comfortable covering, rich and soft feel, comfortable wearing, and breathability. Comparable taking performance, thus winning a broad market. As people have higher and higher requirements for the color fastness of clothing fabrics, they also have high requirements for the washing color fastness of printed and dyed polyester/spandex products. For example, six-fiber staining is level 4, and the color fastness to immersion is level 4 to 5.
Production process
Polyester and ammonia knitted fabric → degreased and washed (loose type pre-shrunk washing machine, 60~95℃, 7 tanks) → pickled (glacial acetic acid 0.5 g/L) → pre-shaped (195~ 205℃, 15 m/min) → Dyeing (130℃, 50 min) → Acid reduction cleaning (90°C, 15 min) → Alkaline reduction cleaning (90°C, 15 min) → Acid neutralization (glacial acetic acid 0.5 g/ L) →Finished product shaping (130～140℃, 15～30 m/min) →Test.
Production process
1. Pretreatment
1.1 Refining and degreasing water washing
Principle: Polyester-span elastic fabric contains a lot of spinning and weaving oils, spandex amino silicone oil, which must be completely removed before dyeing to prevent oil Such substances form color lakes with dyes, causing problems such as fabric color flowers and color stains. However, silicone oil agents are difficult to remove using ordinary scouring conditions and are the main cause of dyeing defects such as stains. Therefore, spandex-specific scouring agents must be used to fully perform the scouring process.
Refining equipment:
Choose continuous heated spray type Loose-type pre-shrinking washing machine (more than six sections), loose-type pre-shrinking washing machine can effectively remove oil substances while ensuring that the cloth surface does not wrinkle, which is beneficial to the smoothness of the cloth surface after dyeing.
Refining prescription: high-efficiency refining emulsifier 20-30 g/L, soda ash 2g/L
Cloth-dropping requirements: The cloth-dropping needs to be done in time after oil removal and water washing; the pH value of the cloth surface is ≤7.5; the less high-efficiency scouring emulsifier remains on the cloth surface, the better, and it is required to be washed clean. In order to ensure that the cloth surface is clean, the pre-shrinking effect is optimal, and the grease on the cloth surface is cleanly removed, the vehicle speed should be set based on the weight of the fabric to 15-30 m/min.
1.2 Pre-shaping
Principle: Polyester-span elastic knitted fabrics are During the weaving process, the presence of large residual stress inside the gray fabric will cause the fabric structure to deform. If the residual stress in this area is not eliminated, problems such as creases and stripes may easily occur during the dyeing process of the fabric. At the same time, the width and weight of the fabric will be difficult to control, and shrinkage will be unstable.
The purpose of pre-shaping is to eliminate the internal stress of spandex and stabilize the quality indicators such as fabric width, unit area quality and fabric elasticity to prevent it from shrinking during the dyeing process. It affects the dyeing effect and will not change significantly in subsequent processes. The quality of the pre-forming effect will directly affect the subsequent processes. If the pre-forming temperature is too low and the speed is too fast, the wrinkles on the cloth surface will not be easily removed, and it is easy to form broken marks, curling and unstable width during dyeing. ; If the pre-setting temperature is too high, the fabric will turn yellow and hard, and its strength and elasticity will decrease, and even the spandex will break.
Therefore, the preforming process conditions must be strictly controlled. There must be a certain positive overfeed during preforming, and the rolling car tension rod must be lowered.
Shaping equipment: eight-section or ten-section open width shaping machine.
Pre-forming process: clean water in rolling car, rolling car pressure 5 N/cm2, setting machine temperature 195~205℃, vehicle speed 18~30 m/min, overfeeding 15% .
The cloth dropping requirements: the cloth surface is flat; the cloth is dropped on a breathable net bucket (to prevent heat pressure creases); when necessary, the air volume should be appropriately increased to achieve timely cooling of the cloth surface (swinging) for heat dissipation. The final cloth surface temperature is required to be normal temperature).
2. Dyeing
2.1 Dye Selection
Disperse dyes generally stain spandex seriously. When selecting disperse dyes, you must consider that they have good coloring properties and good dyeing properties. At the same time, the staining on spandex can be easily removed. When dyeing with ordinary disperse dyes, the spandex fiber is stained seriously and is not easy to remove. In the end, the fastness indicators of polyester and spandex fabrics do not meet customer needs.
2.2 Dyeing equipment
High temperature and high pressure overflow jet dyeing machine: The use of an overflow dyeing machine can reduce the tension and pulling force endured by polyester and spandex fabrics at high temperatures without causing damage to the elasticity of polyester and spandex fabrics, keeping the fabric in a relaxed state and avoiding shrinkage.
2.3 Dyeing process
Disperse dye dyeing requires high temperature and high pressure, polyester The fiber has a better coloring effect under high temperature conditions, but spandex is not resistant to high temperatures. Under high temperature conditions, spandex yarns are prone to brittleness, resulting in reduced strength, broken wires, defects and other problems. Therefore, in order to balance polyester and spandex fibers, after testing and production According to research, the dyeing temperature of 130°C can satisfy the coloring conditions of polyester and better avoid damage to spandex.
Similarly, dyeing time, dyeing pH value, heating rate and cooling rate will all cause damage to spandex fibers. After experiments and mass production tests, in order to reduce damage to spandex, the dyeing time was selected to be 40 minutes, the dyeing pH value was 3.8 to 4.5, and the dyeing temperature rise was controlled within 1.°/min. If the temperature rises too fast, it will be caused by insufficient holding time. Color flowers, the cooling should be controlled at 1-1.5 °C/min, because cooling too fast will cause chicken paw marks and even color flowers.
2.4 Restoration Cleaning
DetergentIn the dyeing of ammonia knitted fabrics, the staining of spandex by disperse dyes is inevitable. The purpose of reduction cleaning is to remove the floating color on the fabric and the disperse dye adsorbed on the spandex surface, and improve the color fastness of the fabric to washing.
Restore cleaning should not only effectively remove the floating color on the fabric and the stain on the spandex, but also consider that the discoloration of the fabric should be within a controllable range. After a period of time In on-site practice, we adopt the following reduction cleaning method, which achieves various fastness indicators to meet customer requirements. At the same time, the discoloration caused by reduction cleaning of fabrics is also within the controllable range.
Generally, polyester fabrics dyed in dark colors only need alkaline reduction cleaning, but for polyester and polyurethane knitted fabrics. In order to completely remove the floating color on polyester and the staining on spandex, after continuous experiments in large-scale production, it was found that after dyeing polyester and spandex fabrics, adding an acidic reduction cleaning before alkaline reduction cleaning can significantly improve the setting Color fastness of finished polyurethane knitted fabric.
The analysis reason may be: adding thiourea dioxide immediately after polyester ammonia dyeing for acid reduction cleaning, which not only saves the drainage and acid neutralization water washing, shortens the process flow, but also It can effectively initially remove floating color on polyester and staining on spandex, ensuring sufficient reaction in the next step of alkaline reduction cleaning, further removing residual floating color and staining, thereby effectively improving the color fastness of polyester and spandex fabrics. Spend.
Reduction cleaning method: The dyed polyester and ammonia fabric is reduced and washed using a two-bath and two-step combination process, with acidic reduction cleaning first and then alkaline reduction cleaning.
Alkaline reduction cleaning process prescription: 36Be NaOH 3.0%, insurance powder 4.0%
2.5 Fastness test before leaving the tank
Water immersion fastness test:
5～6 g/L product Soak Diaopai laundry detergent in heated water at 85°C for 3 to 4 minutes. At the same time, put in undyed polyester-spandex fabric interlining to see how the color of the foot water is. After testing, the color faded slightly due to water on the feet, and the interlining containing spandex of the same fiber hardly stained.
Finished product shaping
Polyester and polyurethane fabrics need to be finished as soon as possible after dyeing Set the shape and do not store it for too long after dyeing. Leaving it for too long will easily cause creases and color migration. Like pre-shaping, the whole process of setting the finished product is low tension, and the fabric to be determined is evenly and loosely distributed in the cloth car. Under the condition of ensuring that the surface of the polyester and polyurethane fabric is smooth and wrinkle-free, the setting temperature should not be too high.
Shaping equipment: eight-section open width shaping machine.
Shaping process: the temperature is controlled at 110~130℃; the speed is 20~30 m/min; the addition of feel additives can be done in the feeding trough, and the rolling pressure is 4 N/ cm2. </p
